Lung cancer continues to be the leading cause of cancer related deaths in the United States and worldwide. Despite advances made in understanding and treatment of the disease, the long-term survival rate has remained low. The overall 5-year survival rate is 15% and has not improved significantly over the past few decades.
The heterogeneity of histopathologic subtypes within lung cancer remains a major roadblock to understanding the origin and the course of the disease. The WHO 1996 classification identifies four major histopathological types of lung carcinomas: small cell, squamous cell, adenocarcinoma and large cell. The last three groups combined are referred to as non-small-cell lung cancers (NSCLC) and constitute approximately 80% of all lung cancers.
NSCLC is a heterogeneous group with variability in terms of histological composition, prognostic signatures, and clinical outcomes yet the histopathologic subtypes falling under the common NSCLC umbrella tend to be approached with a common therapeutic strategy. To date, the list of validated prognostic factors for NSCLC patients remains limited. Tumor Node and Metastasis (TNM) staging system and performance status are currently the only validated predictors for the disease, and development of additional prognostic biomarkers is critically needed. While TNM scoring is used to plan treatment and offers prognostic insight, there is a wide spectrum of treatment response and metastatic behavior in NSCLC patients with tumors within the same stages.
There were 228,000 estimated cases of new lung and bronchus cancer is 2013, and approximately 40% of these were patients diagnosed with lung adenocarcinoma. An estimated 20% of new NSCLC adenocarcinoma cases are Stage I patients as determined by current staging systems. Stage I patients are typically not given adjuvant chemotherapy post surgery, while most stage II and III patients are. Unlike other types of cancer, where early diagnosis has significant survival advantages, some 35% to 45% of people with stage I lung cancer die within five years due to recurrent disease, despite successfully surgery.